Fuchsia: Deploy packages using Amber HTTP blob pull mechanism.

Replaces the existing scp & "pm install" based deployment
workflow with one which provisions temporary TUF repositories,
stages packages into the repo, and installs them onto the device
using "amber_ctl get_up". Amber will pull in the blobs it needs
via HTTP.

Refactor port forwarding functions to common.py, as they are
required by "pm serve".

Bug: 895627
Change-Id: Ia2f9527d872bad19a2f245f0264b30279b303cad
Reviewed-on: https://chromium-review.googlesource.com/c/1362248
Commit-Queue: Kevin Marshall <kmarshall@chromium.org>
Reviewed-by: Wez <wez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#617457}
5 files changed